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Abstract  

Two new simple methods were studied for the analysis of radium in fresh waters by concentration and purification. Both methods are based on the use of an inorganic selective adsorber, namely basic lead rhodizonate, LERHO, and partially reduced tin dioxide (PRTD). The procedures were checked by using filtered fresh waters spiked with 0.1 Bq of226Ra, and in the presence of few μg/l of barium. In each experiment133Ba radioisotope was added to water samples to measure the yield of the overall procedure by γ-counting. Barium and radium were adsorbed from basic solutions on LERHO packed chromatographic column in the first procedure, while batch experiments were preferred for the adsorption on PRTD. After separation,226Ra and barium were eluted from the exchangers and co-precipitated onto small filters as thin film, supported on an inactive barium sulphate substrate, to be submitted to alpha-and gamma-spectrometry. Both methods gave promising results.

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Abstract  

The adsorption conditions of uranium, neptunium, thorium, europium on the adsorbers containing the benzylate salts of the 8-hydroxyquinoline (adsorber B), and of 2-methyl- 8-hydroxyquinoline (adsorber R), were prepared, supported onto charcoal and compared with an adsorber, containing the benzylic acid, (G), stabilized with d-glucoseamine, and adsorbed onto charcoal as well. Thorium, protoactinium, and europium are adsorbed nearly completely from aqueous solutions at a large pH range, even in low acid medium, whereas uranium and neptunium are completely adsorbed only from basic solutions of pH 9. The actinides are preferentially adsorbed with respect to other ions, which are present in natural waters, such as calcium or magnesium. This feature make the analysis of most actinides in natural waters easily to be performed without changing the pH of the original system. The uranium (neptunium) analysis indeed may be accomplished after adjusting the original pH to a fairly basic value (about to 9). The adsorption experiments from real samples showed that the analysis of the actinides dispersed in natural water systems may be successfully performed after previous concentration on the adsorbers prepare.

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Abstract  

Uranium and thorium were analyzed in commercial bottled waters and in fresh waters, such as tap water, by neutron activation analysis. The analysis was applied after a preconcentration step from a batch of 1–3 dm3 water under investigation. The adsorption was performed in the presence of a small amount (about 1 g) of an adsorber derived from the salt of a-hydroxyquinoline and benzilic (diphenylglycolic) acid, adsorbed onto charcoal. The preconcentration method has shown to be rapid and reliable. The overall method was set in order to have an alternative method of comparison with other different methods of analysis. The proposed method may be applied to different fresh water samples.

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Abstract  

We studied the preparation of some specific adsorbers capable of isolating and concentrating actinides. Bases of the 8-hydroxyquinoline family, diphosphineamine and tribenzylamine, salted by benzohydroxamic, benzylic or phthalic acid, are able to complex actinides in different oxidation states. As a result of the presence of the benzene rings, all the compounds are easily incorporated into active charcoal to obtain adsorbers with a highly specific surface. The adsorption behaviors of uranyl U(VI) ion, thorium(IV) and Eu(III) were studied by evaluating their distribution coefficients, K d. Results show that all the prepared salts can adsorb the ions in the III and IV oxidation state from weak acid solutions, whereas uranyl ion is adsorbed mainly from weak basic solutions. The prepared compounds can be used successfully to absorb and concentrate actinides from nearly neutral solutions, such as natural waters. The 8-hydroxyquinoline salt of the benzylic anion showed the highest adsorption values and thus seems to be the most appropriate salt to use in the analysis of actinides in water.

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Abstract  

The dietetic contribution of some bioelements, namely sodium, potassium, chromium, manganese, copper, zinc, bromine and lanthanum from rice grains was investigated by destructive neutron activation analysis. Three different species of rice grains, all grown in the Po river valley, were studied on account of different industrial treatments they had been submitted to. Radiochemical separations were carried out by means of inorganic adsorbers such as hydrated antimony pentoxide, metallic cadmium, tin dioxide and manganese dioxide. Results are presented and discussed. Precision and accuracy of the method is discussed as well. A depletion of the mineral content of the rice grains related to the different industrial treatments was established together with an enrichment of bromine in the treated grains.

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Characterisation of lead rhodizonate as barium and radium adsorber from fresh water

I. Preparation and characterisation of lead rhodizonate

Journal of Radioanalytical and Nuclear Chemistry
Authors:
M. Valentini Ganzerli
,
L. Maggi
, and
V. Crespi Caramella

Abstract  

A new adsorber for concentrating barium and radium from diluted solutions and from fresh waters was prepared. It consists of basic lead rhodizhonate, namely [Pb(OH)]2C6O6·PbC6O6·H2O, supported on activated charcoal. It was named LEHRO. Preparation conditions, solubility and barium, or radium, adsorption from solutions of different pH were investigated.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
M. Ganzerli-Valentini
,
S. Meloni
,
V. Caramella-Crespi
, and
P. Borroni

Abstract  

The adsorption of about 50 ions on molybdenum dibromide, (Mo6Br8)Br4·2H2O, in nitric acid was investigated. The preparation of the adsorber and its characterization is presented and discussed. Adsorption mechanism studies were carried out for some noble metals and chromium. Sorption cannot be ascribed to ion exchange mechanism but to formation of insoluble species, and to settlement of few ions into surface sorption sites or into a limited number of cavities in the cluster crystal structure of the adsorber.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
M. Valentini Ganzerli
,
L. Maggi
,
V. Crespi Caramella
, and
G. Premoli

Abstract  

Batchwise measurement of distribution coefficients of earth alkaline metals, on LERHO, lead rhodizonate supported on charcoal, were studied. The adsorption appears to be related to solubility of barium and lead rhodizonates. Preliminary column experiments were carried out as well to check that LERHO is suitable for achieve the preconcentration of radium from extremely diluted solutions. The overall behavior was studied in order to apply it to radiochemical separations.

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Abstract  

Neutron activation analysis of palladium, iridium, platinum, gold, silver and copper in different matrices was carried out by using inorganic adsorbers such as molybdenum dibromide, zinc ferrocyanide and cadmium metal for their radiochemical separation. The matrices chosen to show the versatility of the method were: high-purity copper and nickel metals, NBS standard reference material SRM 1571 (Orchard leaves), Pultusk meteorite and the U. S. Geological Survey standard rock W-1. The method elaborated is very simple as it involves only a few steps and it has been shown to be accurate and capable of yielding reliable results.

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